1. Field of the Invention
The present invention relates to a recording apparatus including an image-erasing device which thermally erases images recorded on a recyclable heat-sensitive sheet and an image-recording device which thermally records images on a recyclable and/or an unrecyclable heat-sensitive sheet.
2. Related Art Statement
There is known a reusable or recyclable heat-sensitive sheet (hereinafter, referred to as the "recycle" sheet) on which images are recorded by heating to a first prescribed temperature and from which the images recorded thereon are erased by heating to a second prescribed temperature higher than the first temperature. This sheet can be recycled many times. Various sorts of recycle sheets are disclosed in Publications No. 57-89993 and No. 63-39377 of unexamined Japanese Patent Applications and U.S. Pat. No. 5,231,505. Meanwhile, there has been known an unrecyclable heat-sensitive sheet (hereinafter, referred to as the "non-recycle" sheet) on which images are recorded by heating to a first temperature but from which the images recorded thereon are not erased by heating to a second temperature higher than the first temperature.
There has been proposed a recording apparatus including (a) an image-erasing device which thermally erases images recorded on a recycle sheet and (b) an image-recording device which thermally records images on a recycle or non-recycle sheet. The recording apparatus additionally includes, as shown in FIG. 7, a sheet cassette 200, and a sheet feed roller 201 for taking out the top one of recycle or non-recycle sheets 202 stacked in the cassette 200 and feeding the thus taken-out sheet 202 toward a first pair of sheet-guide members 207.
In a first case where the sheets 202 stacked in the cassette 200 include only imaged recycle sheets 202a each of which is a recycle sheet with images recorded thereon, the images on each recycle sheet 202a are erased by the image-erasing device before new, desired images are recorded on the thus recycled sheet 202a by the image-recording device. In this case, a nipper roller 203a which cooperates with a heater roller 203b to serve as the image-erasing device, is placed at a position, A, indicated in solid lines, so that the two rollers 203a, 203b nips the imaged recycle sheet 202a and convey the sheet 202a toward a second pair of sheet-guide members 204 while the heater roller 203b heats the imaged sheet 202a for erasing the images thereon. Meanwhile, in a second case where the sheets 202 stacked in the cassette 200 include only image-free recycle sheets 202a each of which is a recycle sheet without any images thereon, desired images are recorded on each recycle sheet 202a by the image-recording device without previous image erasing by the image-erasing device. In the second case, the nipper roller 203a is placed at a position, B, indicated in two-dot chain lines, so that the two rollers 203a, 203b do not nip the recycle sheet 202a so as to permit the sheet 202a to be conveyed toward the second sheet-guide members 204. Thus, the heater roller 203b does not heat the recycle sheet 202a. In either case, when the recycled or image-free recycle sheet 202a reaches a platen 205, a recording head 206 thermally records desired images on the recycle sheet 202a and thereafter the thus imaged sheet 202a is outputted from the recording apparatus.
In the above-described first case, however, the time duration from the previous image erasing on an imaged recycle sheet 202a to the subsequent image recording on the recycled sheet 202a is very short, and thus the stability of image-developing function of the recycle sheet 202a is considerably low at the time of the image recording. On the other hand, in the second case where images are recorded on an image-free recycle sheet 202a without previous image erasing, the stability of image-developing function of the recycle sheet 202a is considerably high at the time of the image recording because the recycle sheet 202a has not been heated by the image-erasing device immediately before the image recording. Therefore, for the first and second cases, the recording head 206 of the image-recording device should be supplied with different drive energies for effecting the image recording with sufficiently high recording quality. However, the above recording apparatus supplies a constant or common drive energy to the image-recording device for the two different cases. Consequently the image recording is carried out with excessively high or low amount of drive energy and therefore well-defined or clear images are not obtained.
In a third case with the above recording apparatus where the sheets 202 stacked in the cassette 200 include only non-recycle sheets 202b, images are recorded on each non-recycle sheet 202b in such a manner that the nipper roller 203a is placed at the position B so that the two rollers 203a, 203b do not nip the non-recycle sheet 202b for permitting the sheet 202b to be conveyed toward the second sheet-guide members 204. In this case, therefore, the heater roller 203b does not positively heat the non-recycle sheet 202b. However, a common path is used for conveying both the recycle and non-recycle sheets 202a, 202b, and the heater roller 203b of the image-erasing device is heated to an image-erasing temperature (e.g., about 150.degree. C.) higher than an image-developing temperature (e.g., about 60.degree. C.) of the non-recycle sheets 202b. Thus, in the recording apparatus, the temperature of the image-erasing device (or heater roller 203b) must decrease to a temperature lower than the image-developing temperature of the non-recycle sheets 202b, before each non-recycle sheet 202b passes through the image-erasing device. In other words, the recording apparatus needs an additional cooling time in the case where images are recorded on a non-recycle sheet 202b immediately after images have been recorded on a recycle sheet 202a. If this cooling time is not taken, well-defined or clear images are not recorded on the sheet 202b, that is, recording quality is lowered. The non-recycle sheet 202b may even be "burned" partly or entirely by the heater 203b.